Aromatic recovery using hydrogen fluoride and copper fluoride



NOV. 24, 1959 D. A. Mcc u ETAL 2,914,584

AROMATIC RECOVERY USING HYDROGEN FLUORIDE AND COPPER FLUORIDE Filed June25, 1958 mu ussv INVENTORS David A. McCall/0y Arthur I? Lien Q n MK R VA m R mmmmqi RQEQ R mm k v QEQQ Y Q hi (I: 8 I kmmmnimumm NR vnmfiqmvmmm \um\. I E m l5 iQGQEkm 5 E in kmmmikm w\ km & kmummou w Q mmmm IVE AROMATIC RECOVERY USING HYDROGEN FLUORIDE AND COPPER FLUORIDEDavid A. McCaulay, Homewood, and Arthur P. Lien, Highland, 11].,assignors to Standard Oil Company, Chicago, 111., a corporation ofIndiana Application June 23, 1958, Serial No. 743,557

17 Claims. (Ci. 260-674) This is a continuationdn-part of our copendingapplication Serial Number 572,948, filed March 21, 1956 and nowabandoned.

This invention relates to the separation of aromatic hydrocarbons fromnon-aromatic hydrocarbons.

An object of the invention is a separation of aromatic hydrocarbons fromadmixture with non-aromatic hydrocarbons. Another object of theinvention is the separation of polycyclic aromatic hydrocarbons fromnonaromatic hydrocarbons. A particular object of the invention is theremoval of aromatic hydrocarbons from petroleum distillates, such ascatalytic reformates, naphthas and light gas oils. Another object is theseparation of aromatic hydrocarbons from admixture with non-aromatichydrocarbons, which extracted hydrocarbons contain only small amounts ofnon-aromatic hydrocarbons. Other objects will become apparent in thecourse of the detailed description.

It has been found that liquid HP in combination With copper fluoride isan extremely effective agent for the separation of aromatic hydrocarbonsfrom admixture with non-aromatic hydrocarbons. The aromatic hydrocarbonsappear to form an HF-soluble complex with the copper fluoride, in thepresence of liquid HF, and are dissolved into the liquid HF acid phase.

The copper fluorides, namely, cuprous fluoride and cupric fluoride donot appear to react with aromatic hydrocarbons when the two arecontacted. In the presence of liquid hydrogen fluoride, in an amountexceeding the solubility of the HP in the aromatic hydrocarbon, copperfluorides form a complex containing copper fluoride and aromatichydrocarbon. Copper fluoride is essentially insoluble in liquid HFalone. When solid copper fluoride, suflicient liquid HF, and an aromatichydrocarbon are contacted, the solid copper fluoride disappearscompletely, when suflicient aromatic hydrocarbon is present. Bycontrolling the amount of aromatic hydrocarbon and using suflicientliquid HF, it is possible to have the three material's merge into asingle homogeneous solution. That some chemical reaction has occurred isevidenced by the change in color of the liquid HF with particulararomatic hydrocarbons. For example, a solution formed from liquid HF,cuprous fluoride and methylnaph'thalene is a brilliant ruby red incolor. When the aromatic hydrocarbon is in admixture with non-aromatichydrocarbons, a separate HF-insoluble phase, i.e., raiflnate phase, isthen present in the system. This raflinate phase, when analyzed,contains less aromatic hydrocarbon than did the original mixture. By theuse of suiiicient copper fluoride and liquid HF, it is possible toproduce a rafiinate phase which is substantially free of aromatichydrocarbons, i.e., will contain not more than 5 or 6% of aromatichydrocarbons. The degree of aromatic hydrocarbon removal is dependent inpart on the effectiveness of the contacting of the liquid HF, the copperfluoride, and the feed mixture.

.An outstanding characteristic of the liquid HF-copper 2,914,584Patented N ov. 24, 1959- fluoride extracting agent is the fact that theextract recovered from the acid phase is substantially free ofnon-aromatic hydrocarbons, even in a one-step contacting operation,i.e., the extract generally contains in excess of 93-94 mole percent ofaromatic hydrocarbon.

The amount of aromatic hydrocarbon extracted is dependent on the amountof copper fluoride present in the contacting zone and also on the amountof liquidHF present therein. Providing sufiicient liquidHF to form adistinct separate acid phase is present, even trace amounts of copperfluoride will markedly reduce the aromatic content of the rafiinatephase. The two copper fluorides do not behave in the same manner withrespect to extraction efliciency. Cuprous fluoride appears to form acomplex which contains 2 moles of V aromatic hydrocarbon per mole ofcuprous fluoride; thus,

I a complex which contains only 1 mole theoretically, the use of 0.5mole of cuprous fluoride per mole of aromatic hydrocarbon present in thefeed mixture will remove all of the aromatic hydrocarbons into the acidphase. Cupric fluoride appears to form hydrocarbon per mole of cupricfluoride.

More than the theoretical requirement for complete extraction of thearomatic hydrocarbons may be introduced into the contacting zone. Theredoes not appear to be any considerable beneficial result from the use ofamounts much in excess of the theoretical requirement. The excess copperfluoride, when in the form of a powder, tends to accumulate atthe'interface between the raflinate phase and the acid phase and may,'a; under some conditions, interfere'with phase separation, causingraflinate phase to be withdrawn phase. It is preferred to operate eitherof copper fluoride theoretically needed to remove the amount of aromatichydrocarbons wanted to be "ex, tracted, or with theamount theoreticallyneeded-to'extract all the aromatic hydrocarbons present in the feedmixture. -It appears that by the use of an eflicient contacting ofparticularly multi-stage operation, it isf'possible to removevirtuallyall the aromatic hydrocarbons "L from the feed into the acidphase when using 0.5 mole of cuprous fluoride per mole mole of aromatichydrocarbon in the feed mixture.

able commercially does not form a complex with aromatic hydrocarbons inthe presence of HF.

The presence of Water has a deleterious effect on the. extractionefliciency of the liquid HF-copper fluoride extracting agent. Theprocess is essentially anhydrous conditions. fluoride utilized in theprocess should be, anhydrous or essentially so. The commercial gradeanhydrous hydro fluoric acid which contains on the order of 1-2 weightpercent of water is suitable for use in the process.

Some aromatic hydrocarbons can be extracted from a carried out underfeed mixture by the use of copper fluoride in combina-.. tron with justenough liquid HF to form a distinctsepa rate acid phase. The separationefficiency of the agent,

as measured by the moles of aromatic hydrocarbon ex tracted per mole ofcopper fluoride present, increases rapidly as the amounts of liquid HFpresent is increased,-

up to about 3 moles of HF per mole of aromatic hydrocarbon in the feedmixture. More than this amount is helpful in phase separation and inimproving the contacting. It is preferred to operate with between about5 and 15 moles of HF per mole or aromatic hydrocarbon in the feed. It isto be understood that more. than'this amount of HF may be used. Largeamounts of HFare of aromatic along with acid with the amounts.

of aromatic hydrocarbon: 1n the feed mixture or 1 mole of cupricfluoride per The liquid hydrogen.

3 helpful when operating at low temperature with a viscous feed.

Put in another way, the liquid HF usage may be between about 30 and 150volume percent, based on the total feed mixture. This usage of liquid HFis particularly suitable when the feed to the process is a petroleumdistillate containing between about 25 and 75 volume percent of aromatichydrocarbons, for example, a catalytic reformate.

The copper fluoride may be introduced into the contacting zone either inthe form of a solid'powder or as a slurry in the liquid HF or even as adispersion in the feed mixture. Or the solid powder may be introducedinto the HF acid phase present in the contacting vessel. It is preferredto introduce the copper fluoride as a dispersion in the liquid HFportion of the agent.

It appears that all aromatic hydrocarbons will form the complex withcopper fluorides. The aromatic hydrocarbons may contain a single benzenering or contain condensed benzene rings. The aromatic hydrocarbons maycontain substitutents on the ring or may be condensed rings wherein 1 ormore of the rings is paraflinic or olefinic in nature. Examples ofsuitable benzene hydrocarbons are benzene, toluene, xylenes, such asm-xylene, the various other polymethylbenzenes, such as mesitylene,isodurene, and hexamethylbenzene, ethylbenzene and the variouspolyethylbenzenes, isopropylbenzene, and the variouspolyisopropylbenzenes, also the various butyl and pentyl derivatives,such as t-butylbenzene, 2-phenylpentane, etc.; in addition to these, thesubstituted benzene-s containing 2 or more different substituents suchas ethyltoluene, isopropyltoluene, and ethylxylene. Examples of thenaphthalene hydrocarbons which are suitable are naphthalene, the variousmethylnaphthalenes, and polymethylnaphthalenes, ethylnaphthalene and thevarious polyethylnaphthalenes, also the naphthalenes containing propyl,isopropyl, butyl, t-butyl and pentyl substituents. The naphthalenescontaining olefinic substituents are suitable, for example, ethenylnaphthalene, propenyl naphthalene, and pentenyl naphthalene. The variousindanes are suitable. For example, methyl indanes, ethyl indanes,isopropyl indanes, etc. The various dihydronaphthalenes are suitable,such as the methyl, ethyl, propyl, and butyl substituteddihydronaphthalenes. The various tetrahydronaphthalenes are suitable,such as the methyl, ethyl, propyl, t-butyl, and pentyl substitutedtetrahydronaphthalenes.

It is preferred to utilize benzene, naphthalene, and the variousalkylbenzenes and alkylnaphthalenes whose alkyl groups contain not morethan 5 carbon atoms. Examples of these are benzene, ethylbenzene,toluene, metaxylene, naphthalene and ot-methylnaphthalene.

In addition to the aromatic complexes, the copper fluorides also formcomplexes with organo-sulfur compounds, such as mercaptans, thioethers,and disulfides. In general, these organo-sulfur compound-copper fluoridecomplexes are much more stable than are the aromatic hydrocarbon-copperfluoride complexes. It is diflicult to recover the aromatic hydrocarbonfrom these organosulfur compound complexes. It is possible to separate amixture of the aromatic hydrocarbon complex and the sulfur compoundcomplex by decomplexing the aromatic hydrocarbons and separating thedecomplexed aromatic hydrocarbons from the copper fluoride-organo-sulfurcompound complex. In view of the difliculty of decomplexing theorgano-sulfur compounds, it is preferred to operate on a feed mixture ofaromatic hydrocarbons and non-aromatic hydrocarbons which issubstantially free of organo-sulfur compounds.

Olefinic hydrocarbons in the presence of the liquid HF, tend to alkylatethe aromatic hydrocarbons. When it is desired to avoid degradation ofaromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzeneto higher boiling alkyl aromatics, it is preferred to use a feed whichis essentially free of olefinic hydrocarbons.

. content and olefinic hydrocarbon content.

A suitable feed to the separation process of the invention is apetroleum distillate boiling below about 700 F. The distillate boilingbetween about 100 F. and 450 F., i.e., the gasoline range, derived fromthe product of the catalytic reforming in the presence of hydrogen, ofpetroleum naphthas is particularly suitable as a source of aromatichydrocarbons because of its very low sulfur The entire naphtha boilingrange material of the catalytic reformate may be used or any one of thenarrower boiling range cuts closely boiling about a particular aromatichydrocarbon, for example, the benzene fraction, the toluene fraction orthe C aromatic hydrocarbon fraction.

The HF, copper fluoride, feed mixture contacting step may be carried outat a temperature between about 40 C. and 150 C. In general, attemperatures above 150 C., many aromatic hydrocarbons, such as alkylnaphthalenes, undergo crackingreactions with formation of tar and gases.Other aromatic hydrocarbons may be treated at temperatures well inexcess of 150 C. Other sensitive aromatic hydrocarbons may need to betreated at temperatures below 150 C. The process operates veryeffectively at ambient temperatures and for this reason it is preferredto operate at temperatures between about 10 C. and 35 C.

As the contacting step involves a reaction between solid copperfluoride, aromatic hydrocarbons, and probably some liquid HF, maximumextraction efliciency requires that the contacting be carried on for asuflicient time.

The degree of agitation appears to be the controlling factor in theattainment of maximum yields. With efficient agitation, contacting timeson the order of 5 minutes are sufficient. With inetficient agitation,times as much as 1 hour or more may be needed.

It is to be understood that the contacting operation requires thepresence of liquid hydrogen fluoride. Therefore, the contacting zonemust be maintained at a pressure sufliciently high to keep the HF in theliquid state.

The aromatic hydrocanbons pass into the liquid HP to form a solutioncontaining liquid HF and an HP- soluble complex containing copperfluoride and aromatic hydrocarbons. In addition to these, the solutionwill contain physically dissolved non-aromatic hydrocarbons. Also, thesolution will contain organo-sulfur compounds which have reacted withcopper fluoride to form an HP- soluble complex. The complex appears todecompose readily at moderate temperatures. By the time all the HP hasbeen distilled from the distillation zone, there will remain behindprecipitated solid copper fluoride, and possibly some aromatichydrocarbons. in the case of the lower boiling aromatic hydrocarbons,all or substantially all of the aromatic hydrocarbons will also distillover during the recovery operation. The complex of organo-sulfurcompounds and copper fluoride is much more stable than the complex ofaromatic hydrocarbon and copper fluoride. This complex may still bepresent in the distillation zone after HP has ceased to distill over.For example, a solution containing HF, diethyl sulfide, and cuprousfluoride has to be heated to 400 C. at atmospheric pressure for somehours before all the HF had been distilled over and the cuprous fluoriderecovered completely as such.

It is not necessary to decant the non-aromatic rich raflinate phase fromthe liquid HF solution in order to obtain a separation between the twoclasses of hydrocarbons. After the feed mixture has been contacted withthe liquid HF and copper fluoride to form a solution comprising liquidHF and dissolved complex, a nonaromatic hydrocarbon-rich fraction may beobtained by subjecting the feed-liquid HF-copper fluoride admixture todistillation. The first hydrocarbons distilled are the non-aromatichydrocarbons (some aromatic hydrocarbons also appear overhead); with theseparation of these, a liquid HF solution remains containing essentiallypure complexed aromatic hydrocarbons. This liquid HF solution is thendistilled to remove these aromatic hydrocarbons overhead.

This distillative separation method is particularly applicable toaromatic concentrates, e.g., mixtures containing 90 weight percent or ofaromatic hydrocarbons. In this method the copper fluoride is used in anamount of at least on the order of that theoretically needed to complexthe aromatic hydrocarbons in the feed, e.g., usually from about 80% to120% of the theoretical amount.

step laboratory contacting, the extract will contain on the order of94-95% of aromatic hydrocarbons.

The results obtainable with the process of the invention are set out inthe following illustrative examples.

With the exception of Runs and 6, the runs were carried out in aHastelloy autoclave provided with a mechanical stirrer. In these runs,the solid copper fluoride and liquid HF were introduced into theautoclave followed by the particular feed mixture. The cuprous fluorideand cupn'c fluoride were anhydrous powders.

TABLE I Run N0 1 2 3 4 5 6 7 8 Ouprous fluoride, g 11 ll 8 31 37. 5 237. 5 8 7 lli lFa 80 350 100 100 75 60 Toluene, ml 61. 7 58. 0 34. 5 833 39 g. 4 36 n-Heptane, m1 58. 4 52.1 35.5 173 80 72 V01. Percent Aroma51. 4 52. 6 49. 1 32. 4 45 33 Temperature, 0 25 25 25 25 25 25 25 25Ratfinate:Vol.Perecnt Aromatic 37.0 35.7 28.2 4.3 6 6 11 18 Extract:Vol. Percent Aromatic 96. 0 92.0 95 95 100- 94 Arom. in Feed/Cul moles4. 4 4.1 3.1 2.0 2. 8 3. 4 Arom. ExtJCuF, moles 1. 9 2. 0 2.0 1. 9 2.02.0 2.1 1. 7 HF/Feed, Vol. Percent 21 32 93 74 50 63 l Cataly Thedistillative separation method may also be used to obtain very purearomatic hydrocarbons from ordinary feed mixtures when it is not desiredto use paraflin hydrocarbon countersolvent. Thus, a raflinate phase isdecanted from a liquid HF solution phase containing appreciable amountsof non-aromatic hydrocarbons; the liquid HF solution phase is thensubjected to distillative separation to remove as the first overheadfractions the non-aromatic hydrocarbons.

In general, the distillative removal of the HF from the solution may becarried out at temperatures between about 20 C. and 125 C. Pressure hasan important bearing on the temperature which is needed to be used. Atthe lower temperatures, it is necessary to operate with a vacuum on thesystem. Thus, at 20 C. it is desirable to operate with a pressure ofabout 1 mm. Hg. As the temperature is increased, more pressure istolerable on the distillation zone and at about 125 C. it is possible tooperate with a pressure of about 1 atmosphere or even slightly more.Thus, there is a relationship between the temperature and pressure whichmay be set out as the lower the temperature the lower the pressureneeded, or the lower pressures correspond to the lower temperatures. Thedistillation may be continued only for that time needed to remove allthe HF present (disregarding the amount present in complex withorganosulfur compounds), leaving in the distillation zone residue ofsolid copper fluoride and extract hydrocarbons. Or, the distillation maybe continued until all of the extract hydrocarbons have been distilledaway from the distillation vessel leaving solid copper fluorideremaining therein.

7 When extract hydrocarbons and solid copper fluoride have been left inthe distillation zone, the solid copper fluoride may be readily filteredaway from the liquid hydrocarbons.

In the laboratory, the extract hydrocarbons may be readily separatedfrom the acid phase by diluting the acid phase with cold water or diluteaqueous caustic.

solution. The extract forms an upper hydrocarbon phase above a loweraqueous phase. The extract may be then neutralized prior to furtherprocessing, such as distillation into close boiling fractions or evenhigh purity aromatic hydrocarbons. The-total extract containssubstantially only aromatic hydrocarbons. Even in a onetieyRefcrmate:Benzene, toluene, Ca and O9, 45%; olefins, 1%, paraflins and In allcases, commercial grade anhydrous hydrofluoric acid containing about 1weight percent of water was used. The toluene and n-heptane were cp.grade material. In all cases, the contents of the autoclave were stirredfor one hour at ambient temperature. The contents were then permitted tosettle for 10 minutes. The lower acid phase was withdrawn into apolyethylene bucket containing crushed ice. The upper hydrocarbon, i.e.,extract layer was decanted from the lower aqueous layer and neutralizedwith ammonium hydroxide solution. The neutral extract was analyzed bydistillation and infrared spectrometry. The raflinate layer wasneutralized and water-washed and then was analyzed by distillation andinfrared spectrometry.

Table I sets out the data obtained utilizing cuprous fluoride as thecopper fluoride. Runs 1, 2 and 3 were carried out under essentially thesame conditions except for the amount of HF present. These runs showthat over the range of HF to total feed volume ratio of .21 to .93 theamount of toluene extracted was 2 moles per mole for cuprous fluoridecharged. In each of these runs, a considerable excess of toluene waspresent over that complexible by the cuprous fluoride charged. Run 4 wascarried out using the theoretical amount of cuprous fluoride based onthe toluene content of the feed. The toluene extracted per mole ofcuprous fluoride charged was very close to the theoretical. In this run,the extract contained 92 mole percent of toluene and 8% of heptane. Theraflinate contained only 4 mole percent of toluene.

Run No. 7 was carried out using as the feed a mixture of omethylnaphthalene and n-heptane. Slightly more than the expected 2 molesof methylnaphthalene per mole of cuprous fluoride charged was taken intothe acid phase. Also, the purity of the extract was greater than workingwith toluene or xylene, as the extract was virtually free of heptane.

Run No. 8 was carried out on a mixture of meta-xylene and para-xylene.The run shows that the cuprous fluoride is almost as effective underthese conditions as with toluene.

Runs 5 and 6 were carried out on a catalytic reformatc obtained fromplatinum reforming of a virgin naphtha. This catalytic reformate wastaken as that material including allof the benzene, toluene, xylene,ethylbenzene and trimethylbenzenes present in the total reformate. Thiscatalytic reformate contained essentially no organo sulfur compounds andonly 1 volume percent of olefin hydrocarbons. In each run, thetheoretical amount of cuprous fluoride was used. In Run No. 5, theextract contained 95% of aromatic hydrocarbons and the raffinate 6% ofaromatic hydrocarbons. The acid phase from Run 5 was pumped at ambienttemperature for 3 hours at a pressure of about 2 mm. Hg. All of thehydrocarbons in the HF were taken overhead leaving solid cuprousfluoride in the flask. This recovered solid cuprous fluoride was used inRun No. 6. The results show that it was fully as effective as the freshcuprous fluoride used in Run No. 5.

Another run under the conditions of Run 6 was carried out. The acidphase was separated from the raffinate phase and the acid phase was thenwashed with isopentane. The hydrocarbon layer was separated from thewashed acid phase. The washed acid phase was then maintained at ambienttemperature at about 2 mm. Hg. pressure until all the HF andhydrocarbons had been dis tilled away from the solid cuprous fluoride.The hydrocarbons were then fractionated into close boiling fractions.Analysis of the close boiling fractions showed that the aromatichydrocarbon fractions were, within the error or infrared spectrometry,free of non-aromatic hydro carbons.

In Table H, there are set out runs utilizing cupric fluoride as thecopper fluoride. These runs show that cupric fluoride gives results onrecovery of toluene from admixture with n-heptane essentially identicalwith those obtained using cuprous fluoride. The big difference be tweenthe fluorides lies in the fact that cupric fluoride removes only 1 moleof toluene per mole of cupric fluoride charged.

Run N0. 11

The feedmixture to this run was an aromatic-rich mixture having abromine number of 3.5 and a sulfur content, Lamp Method, of 0.004 weightpercent. By gas chromatography the mixture contained, on a weight basis,0.7% of hydrocarbons boiling below benzene, 78.7% of benzene, 0.1% ofhydrocarbons boiling above benzene and below toluene, and 20.5% oftoluene. (Fractional distillation of this mixture permitted the recoveryof only two-thirds of the benzene present as nitration grade.

The contacting-distillation was carried in an autoclave provided with amechanical stirrer. Feed was charged in an amount of 40 cc. (36 g.)0.5moles of aromatic hydrocarbon. Liquid HF was charged in an amount of 100cc. (2.5 moles). Cuprous fluoride was charged in an amount of 21 g.(0.25 mole)the theoretical amount needed to complex all the aromatichydrocarbon present. The contents of the autoclave were stirred at about25 C. for 1 hour. A vacuum was then pulled on the autoclave andfractions consisting of HF and hydrocarbons were gradually distilledoverhead and collected in a receiver. The HF was removed from thehydrocarbons in each fraction and the recovered hydrocarbons in eachfraction analysed by gas chromatography. The individual fractionsdistilled and the hydrocarbon analysis are given below:

Hydrocarbon Analyses I-IF Hydro- (Wt. Percent) Fraction Content carbong. Content,

g. Benzene Toluene N on- Aromatic Fractions 5 and 6 were combined andthe benzene separated, by fractional distillation, from the toluene. Thefreezing point of the benzene product was determined in duplicate runsas 5.45 C. and 551 C., which indicates a purity of at least 99.9%.

The annexed figure, which forms a part of this specification, shows apreferred illustrative embodiment of the use of cuprous fluoride inconjunction with liquid HF for the separation of aromatic hydrocarbonsfrom a catalytic reformate. It is to be understood that the illustrativeembodiment set out is schematic in nature and many items of processequipment have been deliberately omitted as these may be readily addedby those skilled in this art.

in this embodiment, the feed is a catalytic reformate boiling betweenabout F. and 370 F. which has been derived from the catalytic reformingof a virgin naphtha. Many catalytic reforming processes are now incommercial use in the petroleum industry, for example, Ultraforming,Catforming, Hydroforrning, Houdritorming, and Platforrning. Thiscatalytic reformate feed contains about 50 volume percent of aromatichydrocarbons. In addition to benzene, toluene, xylenes and ethylbenzene,a small amount of C aromatic hydrocarbons is present. This catalyticreformate contains less than 1% of oleflnic hydrocarbons and on theorder of 0.05 weight percent of sulfur. Feed from source 11 is passed byway of line 12 through drier 13. In drier 13, the water contained in thefeed is removed essentially completely. Drier 13 may consist of awell-known alumina drier followed by chemical drying through lime toremove last traces of water. Any of the well-known techniques forremoving dissolved water from hydrocarbons may be used herein. The driedfeed is passed from drier 13 by way of line 14 into extractor 16 at alower point thereof.

Extractor 16 is a vessel adapted for the continuous countercurrentcontacting of two immiscible liquids. Instead of using a countercurrenttower, a number of individual stages providing countercurrent flow maybe used. Extractor 16, in this embodiment, provides three theoreticalseparation stages.

Extracting agent is passed into extractor 16 at various points throughvalved lines 18, 18a, 18b, and 18c. Extractor 16 is divided intocontacting zones as shown. Each of these contacting zones is agitated bymeans of a turbine-type stirrer 19, 19a, 19b, and 190. The stirrers aredriven by motor 20.

The agent utilized herein contains commercial grade anhydroushydrofluoric acid in an amount corresponding to 55 volume percent, basedon feed from line 14. Solid cuprous fluoride is present to the extent of0.55 mole per mole of aromatic hydrocarbons in the feed from line 14.The agent is in effect a slurry of solid cuprous fluoride in the liquidHF.

In this embodiment, extractor 16 is operated at a constant temperature,over its entire height, of 20 C. and at a pressure of 5 p.s.i.g. inorder to keep the HP in the liquid state. Suflicient contacting time isprovided so that essentially all the aromatic hydrocarbon is extractedby the agent as the feed flows up extractor 16.

From the top of extractor 16, there is withdrawn by.

way of line 21 a raflinate phase which contains a small amount ofoccluded agent. The raflinate phase is passed into coalescer 22, whereinthe occluded agent is separated. The recovered agent is withdrawn fromcoalescer 22 by way of valved line 23 and may be recycled to line 18 forreuse in the process or withdrawn from the system by way of valved line24. Coalescer 22 may be any vessel adapted to facilitate separation ofdispersed immiscible liquid from another liquid, for example, coalescer22 may be filled with steel wool. From coalescer 22, the raffinate ispassed by way of line 26 into HF stripper 27 which is provided withinternal heat exchanger coils 28.

Normally, the extract phase produced in extractor 16 contains only avery small amount of non-aromatic hydrocarbons. When it is desired toproduce an aromatic hydrocarbon product which is free of close boilingnonaromatics hydrocarbons, a low boiling paralfin hydrocarbon may beintroduced into the bottom of extractor 16 to wash from the extractphase these close boiling non-aromatic hydrocarbons. In this embodiment,isopentane from source 31 is passed by way of valved line 32 into line33 and thence into extractor 16. The amount of wash liquid introduced isdependent upon the eflectiveness of extractor 16, but in general, willbe between about 0.1 and 0.5 volumes of isopentane per volume of totalhydrocarbons in the extract phase. In this embodiment, 0.25 volumes ofisopentane per volume of total hydrocarbons in the extract phase areintroduced.

The isopentane introduced into extractor 16 passes out of extractor 16along with the ratfinate phase. Stripper 27 is operated to removeoverhead from the raflinate phase dissolved HF and isopentane. Raflinatehydrocarbons containing less than on the order of 1% of aromatichydrocarbons are withdrawn from the bottom of stripper 27 and passed tostorage not shown by way of line 36.

The HF-isopentane vapors are removed from stripper 27 by way of line 37and are condensed in cooler 38. The total stream may be passed'by way ofvalved line 39 and line 41 to line 33 for reuse in extractor 16. Or,cooler 38 may be designed to act as a separator and a lower phase of HFwithdrawn by way of valved line 42. If it is not desired to recycle theisopentane from line 39, it may be withdrawn from the system by way ofvalved line 43.

An extract phase consisting of liquid HF, cuprous fluoride-aromatichydrocarbon complex and dissolved isopentane is withdrawn from extractor16 and passed by way of line 46 into decomposer 47 which is providedwith an internal heater 48. In this embodiment, decomposer 47 isoperated at a temperature of 30 C. at a pressure of about mm. Hg. for atime of about 1 hour.

Under these conditions, HF and some aromatic hydrocarbons and isopentanepass overhead through line 51. These vapors are condensed in cooler 52and pass by way of line 53 into separator 54. Separator 54 is adaptedfor the gravity separation of two immiscible liquids. A lower phase ofliquid HF is withdrawn from separator 54 by way of line 57. An upperphase of aromatic hydrocarbons and isopentane is withdrawn fromseparator 54 by way of line 58.

From the bottom of decomposer 47, a slurry consisting of aromatichydrocarbons and solid CuF is passed by way of line 61 into washer 62.Washer 62 is a vessel adapted for fluidized contacting of an immiscibleliquid-solid with a wash liquid. In this instance, isopentane from line64 is introduced into washer 62 by way of distributor 66. The amount ofisopentane introduced into washer 62 is suflicient to dissolve all thedecomplexed aromatic hydrocarbon and remove adsorbed aromatichydrocarbon from the surface of solid CuF. The amount of lowboilingparaflinic hydrocarbon used in washer. 62, in general, is betweenabout 0.25 and 1 volume of low boiling parafiinic hydrocarbon such asisopentane per volume .of

slurry charged to washer 62 by way of line 61. Herein 0.5'volume ofisopentane are introduced by way of line.

by the emerging stream. Preferably, two filters are used in parallel sothat one filter may be cleaned to recover CuF without interrupting thecontinuous operation. The filtered material is passed by way of line 71into fractionator 72. The hydrocarbons from line 58 are passed by way ofline '71 into fractionator 72. Fractionator 72 is shown schematically.There is taken overhead isopentane vapors and these are passed byway ofline 73 and line 64 back to Washer 62. Makeup isopentane from source 74is passed by way of valved 'line 76 into line 64.

Aromatic hydrocarbon stream consisting of. benzene, toluene, C aromatichydrocarbons and some C aromatic hydrocarbons is withdrawn from zone 72by way of line 78 and is passed to further processing for thepreparation of essentially pure close boiling aromatic product.

A slurry of CuF in isopentane is withdrawn from washer 62 by way of line81. Liquid HF from line 5 7 is passed by way of line 82 through aneductor not shown, to pick up the slurry from line 81. The slurry ofCuF, isopentane and liquid -HF is passed by'wayof line 83 back tomanifolded line 18 for reuse in extractor 16.

Makeup liquid HF in the form of commercial grade anhydrous hydrofluoric.acid is introduced from source 84 by way of valved line 85 into line 57.

Makeup cuprous fluoride is introduced from source 87 by way of line 88into washer 62. p I

Instead of using the procedure set out in the illustrative embodiment,another form of operation is to use a batch system wherein thecontacting is carried out in one vessel,

the raflinate phase separated and treated to remove dissolved HF andoccluded agent. The acid phase may be Washed with a low boilingparaflinic hydrocarbon in the contacting vessel and the hydrocarbonphase separated and treated for the recovery of the wash hydrocarbon.The acid phase remaining in the contacting vessel is then decomposed byheating at suitable conditions to remove overhead not only the HF butalso the hydrocarbons The HF and hydrocarbons are separated andprocessed as shown in the illustrative embodiment. The solid copperfluoride remains in the contacting vessel and is ready for extraction ofanother batch of mixed feed. By the use of two or more contactingvessels, it is possible to carry out a continuous operation with respectto all parts of the system except the contacting vessels themselves.

Other embodiments may be readily devised and these are intended to beincluded within the scope of the invention.

Thus having described the invention, what is claimed is:

1. A process which comprises contacting, under essentially anhydrousconditions, a feed mixture comprising essentially aromatic hydrocarbonsand non-aromatic hydrocarbons, with copper fluoride and liquid HF, saidHF being present in an amount of at least about 3 moles per mole of saidaromatic hydrocarbon and said copper fluoride being present in an amountof at least on the order of that theoretically needed to form a complexwith said aromatic hydrocarbons, where said HF and said copper fluorideamounts are calculated in excess of that amount needed to form a complexwith complexible organo-sulfur compounds present in said feed, to forman HF solution of a complex containing aromatic hydrocarbon and copperfluoride, separating a fraction comprising non-aromatic hydrocarbonsfrom a fraction comprising liquid HF and dissolved complex, andrecovering aromatic hydrocarbons from said liquid HF fraction.

2. A separation process which comprises contacting, under essentiallyanhydrous conditions, a feed comprising aromatic hydrocarbons andsaturated non-aromatic hydrocarbons, in the substantial absence ofolefinic hydrocarbons, with a fluoride of the class consisting ofcuprous fluoride and cupric fluoride and liquid HF, said HF beingpresent in an amount of at least 3 moles per mole of aromatichydrocarbons in said feed, at a temperature between about -40 C. and 150C., at a. pressure sufficient to keep said HF in the liquid state,separating a raflinate phase substantially free of aromatic hydrocarbonsfrom an acid phase comprising liquid HF and an HF-soluble complexcontaining said fluoride and aromatic hydrocarbons, and recovering fromsaid acid phase an extract consisting substantially of aromatichydrocarbons and wherein the usage of said fluoride in moles per mole ofaromatic hydrocarbon in said feed is at least about that set out in thefollowing schedule:

Said fluoride: Usage Cuprous fluoride 0.5 Cupric fluoride 1.0

where said usage of the defined fluoride and said HF are calculated inexcess of the amount needed to complex complexible organo-sulfurcompounds present in said feed.

3. The process of claim 2 wherein said copper fluoride is cuprousfluoride.

4. The process of claim 2 wherein said copper fluoride is cupricfluoride.

5. The process of claim 2 wherein said feed is a petroleum distillateboiling below about 700 F.

6. The process of claim 2 wherein said feed is a catalytic reformate.

7. The process of claim 2 wherein said temperature is between about C.and 35 C.

8. The process of claim 2 wherein said HF is present in an amountbetween about 5 and moles per mole of aromatic hydrocarbon in said feed.

9. The process of claim 2 wherein said feed is substantially free oforgano-sulfur compounds.

10. The process of claim 9 wherein said acid phase is maintained at atemperature between about C. and 125 C. at a pressure between about 1mm. Hg. and about 1 atmosphere, the lower pressures corresponding to thelower temperatures, until all of the HP has been distilled away, leavingsaid fluoride in the solid state in z the distillation zone.

ll. A process for separating aromatic hydrocarbons from non-aromatichydrocarbons, which process cornprises (1) under essentially anhydrousconditions, contacting a mixture of aromatic hydrocarbons and saturatednon-aromatic hydrocarbons, said mixture being substantially free ofolefinic hydrocarbons and organosulfur compounds, with liquid HF, in anamount between about 20 and 150,volume percent based on said mixture,and a fluoride selected from the class consisting of cuprous fluorideand cupric fluoride, wherein when cuprous fluoride is said fluorideabout 0.5 mole of cuprous fluoride are present per mole of aromatichydrocarbon in said mixture and when cupric fluoride is said fluoride,about 1 mole of cupric fluoride is present per mole of aromatichydrocarbon in said feed, at a temperature between about 10 C. and 35 C.and a pressure at least suflicient to keep said HF in the liquid state,(2) separating a rafl'inate phase from an acid phase which comprisesliquid HF and a complex containing said fluoride and aromatichydrocarbons, (3) and distilling HF from said acid phase at atemperature between about 20 C. and 125 C. at a pressure between about 1mm. Hg. and about 1 atmosphere, the lower pressures corresponding to thelower temperatures to recover said fluoride and a hydrocarbon productconsisting substantially of aromatic hydrocarbons.

12. The process of claim 11 wherein said distillation is continued untilessentially all of the hydrocarbons in said acid phase have distilled,leaving solid fluoride in said distillation zone.

13. The process of claim 11 wherein said mixture is a catalyticreformate boiling in the gasoline range.

14. An aromatic hydrocarbon recovery process which comprises, underessentially anhydrous conditions, contacting a feed comprisingessentially aromatic hydrocarbons and non-aromatic hydrocarbons with atleast about 3 moles of liquid HF per mole of aromatic hydrocarbons insaid feed and at least about the amount of copperv fluoridetheoretically needed to form a complex with the aromatic hydrocarbons insaid feed, where said HF and said copper fluoride amounts are calculatedin excess of that amount needed to form a complex with complexibleorgano-sulfur compounds present in said feed, to form a solutioncomprising liquid HF and a complex containing copper fluoride andaromatic hydrocarbon, distilling a fraction comprising non-aromatichydrocarbons and HF from a fraction comprising liquid HF and dissolvedcomplex and distilling HF and aromatic hydrocarbons from said liquid HFfraction.

15. The process of claim 14 wherein said feed contains at least aboutvolume percent of aromatic hydrocarbons.

16. The process of claim 14 wherein said HF usage is between about 5 and15 moles per mole of aromatic hydrocarbon.

17. The process of claim 14 wherein said distillation is carried out atbetween about 25 and C.

No references cited.

1.A PROCESS WHICH COMPRISE CONTACTING UNDER ESSENTIALLY ANYHYDROUSCONDITIONS, A FEED MIXTURE COMPRISING ESSENTIALLY AROMATIC HYDROCARBONSAND NON-AROMATIC HYROCARBONS WITH COPPER FLUORIDE AND LIQUID HF,SAID PERMOLE OF SAID AROMARTIC HYDROCARBON AND SAID COPPER FLOURIDE BEINGPRESENT IN AN AMOUNT OF AT LEAST ABOUT 3 MOLES FULORIDE BEING PRESENT INAN AMOUNTOF LEAST ON THE ORDER OF THAT THEORETICALLY NEEDED TO FORM ACOMPLEX WITH SAID AROMATIC HYDROCARBONS, WHERE SAID HF AND SAID COPPERFLUORIDE AMOUNTS ARE CALCULATED IN EXCESS OF THAT AMOUNT NEEDED TO FORMA COMPLEX WITH COMPLEXIBLE ORGANO-SULFUR COMPOUNDS PRESENTS IN SAIDFEED, TO FORM AN HF SOLUTION OF A COMPLEX CONTAINING AROMATICHYDROCARBON AND COPPER FLUORIDE, SEPARATING A FRACTION COMPRISINGNON-AROMATIC HYDROCARBONS FROM A FRACTION COMPRISING LIQUID HF ANDDISSOLVED COMPLEX, AND RECOVERING AROMATIC HYDROCARBONS FROM SAID LIQUIDHF FRACTION.